Delayed Achilles tendon rupture presentation: Non-operative management may be the SMART choice.

INTRODUCTION: This biomechanical study aims to assess the function of patients who were treated non-operatively for delayed diagnosis Achilles tendon rupture. Patients were treated using the Swansea Morriston Achilles Rupture Treatment protocol (SMART), which is a physiotherapy led non-operative treatment program. METHODS: 19 patients (16M:3F) were enrolled and prospectively assessed using Achilles Repair Scores (ARS)/Achilles Tendon Rupture Scores (ATRS) (PROMS), Ankle ROM and isokinetic peak torque for plantarflexion of the ankle. MRI scans of both the injured and uninjured TA were performed to compare both AP diameter and length. RESULTS: Both ATRS and ARS improved between short- and long-term follow-up. The mean difference in plantar torque between the injured and uninjured leg was 21.9%. There was no significant difference in ankle plantarflexion or dorsiflexion. There was no significant difference in length of the injured and uninjured TA on MRI. Three patients failed the SMART protocol requiring surgical fixation. DISCUSSION: The SMART protocol can be an effective method of treatment even in younger and active patients especially if delay to treatment is less than 12 weeks. It may still be preferable for patients with a large gap size or high functional demand to elect for surgical intervention, but clinicians should consider the SMART protocol as an alternative to surgery and discuss it with some patients as a viable alternative.

Development of a criterion method to determine peak mechanical power output in a countermovement jump.

There is a general agreement that the most valid method of measuring peak lower-body mechanical power output (LBPP) in a countermovement jump (CMJ) is by analysis of the corresponding vertical component of the ground reaction force (VGRF)-time history of the jump. However, there is no published standard protocol. The purpose of this study was to establish a standard protocol. The variables necessary to define a valid and reliable CMJ method were: (a) vertical force range, (b) force sampling and integration frequency, (c) method of integration, (d) determination of body weight (BW), and (e) determination of the initiation of the CMJ. Countermovement jumps off a force platform (FP) were performed by 15 male professional rugby players. The 5 variables were then optimized to maximize the reliability and validity of the measure of LBPP. Errors of <1% (p ≤ 0.05) in the measurement of LBPP were obtained using the following specification: (a) 6 times BW (using a 16-bit analog to digital converter), (b) 1,000 Hz, (c) Simpson's rule or the trapezoidal rule, (d) mean VGRF for 1 second of quiet standing immediately before jump signal, and (e) 30 ms before the instant BW ± 5 SD is exceeded after the jump signal. Peak lower-body power output was most sensitive to variables 4 and 5. It was concluded that this study has established a standard protocol for the criterion method of measuring peak power in a CMJ using an FP. As all other estimates and less reliable methods of determining LBPP in a CMJ rely on the FP method for calibration, it is proposed that this protocol be used as the basis of future criterion measures using a FP.

Relationships between force-time characteristics of the isometric midthigh pull and dynamic performance in professional rugby league players.

There is considerable conflict within the literature regarding the relevance of isometric testing for the assessment of neuromuscular function within dynamic sports. The aim of this study was to determine the relationship between isometric measures of force development and dynamic performance. Thirty-nine professional rugby league players participated in this study. Forty-eight hours after trial familiarization, participants performed a maximal isometric midthigh pull, with ∼120-130° bend at the knee, countermovement jump (CMJ), and a 10-m sprint. Force-time data were processed for peak force (PF), force at 100 milliseconds (F100ms), and peak rate of force development (PRFD). Analysis was carried out using Pearson's product moment correlation with significance set at p < 0.05. The PF was not related to dynamic performance; however, when expressed relative to body weight, it was significantly correlated with both 10-m time and CMJ height (r = -0.37 and 0.45, respectively, p < 0.05). The F100ms was inversely related to 10-m time (r = -0.54, p < 0.01); moreover, when expressed relative to body weight, it was significantly related to both 10-m time and CMJ height (r = -0.68 and 0.43, p < 0.01). In addition, significant correlations were found between PRFD and 10-m time (r = -0.66, p < 0.01) and CMJ height (r = 0.387, p < 0.01). In conclusion, this study provides evidence that measures of maximal strength and explosiveness from isometric force-time curves are related to jump and sprint acceleration performance in professional rugby league players.

Effect of postactivation potentiation on swimming starts in international sprint swimmers.

The aim of this study was to investigate the effects of postactivation potentiation (PAP) on swim start performance (time to 15 m) in a group of international sprint swimmers. Nine international sprint swimmers (7 men and 2 women) volunteered and gave informed consent for this study, which was approved by the university ethics committee. Initially, swimmers performed a countermovement jump (CMJ) on a portable force platform (FP) at baseline and at the following time points ∼15 seconds, 4, 8, 12, and 16 minutes after a PAP stimulus (1 set of 3 repetitions at 87% 1 repetition maximum [RM]) to individually determine the recovery time required to observe enhanced muscle performance. On 2 additional days, swimmers performed a swim start to 15 m under 50-m freestyle race conditions, which was preceded by either their individualized race specific warm-up or a PAP stimulus (1 set of 3 repetitions at 87% 1RM). Both trials were recorded on 2 cameras operating at 50 Hz with camera 1 located at the start and camera 2 at the 15-m mark. Peak vertical force (PVF) and peak horizontal force (PHF) were measured during all swim starts from a portable FP placed on top of the swim block. A repeated measures analysis of variance revealed a significant time effect with regard to power output (PO) (F = 20.963, p < 0.01) and jump height (JH) (F = 14.634, p < 0.01) with a paired comparison indicating a significant increase in PO and JH after 8 minutes of recovery from the PAP stimulus. There was a significant increase in both PHF and PVF after the PAP stimulus compared to the swim-specific warm-up during the swim start (PHF 770 ± 228 vs. 814 ± 263 N, p = 0.018; PVF: 1,462 ± 280 vs. 1,518 ± 311 N, p = 0.038); however, time to 15 m was the same when both starts were compared (7.1 ± 0.8 vs. 7.1 ± 0.8 seconds, p = 0.447). The results from this study indicate that muscle performance during a CMJ is enhanced after a PAP stimulus providing adequate recovery (∼8 minutes) is given between the 2 activities. In addition, this study demonstrated that swimmers performed equally well in terms of time to 15 m when a PAP stimulus was compared to their individualized race specific warm-up and indicates that PAP may be a useful addition to a warm-up protocol before races. However, more research is required to fully understand the role PAP plays in swim performance.

Strength and power predictors of swimming starts in international sprint swimmers.

Start performance (as defined by time to 15 m) has been shown to be a key performance indicator during 50-m freestyle swimming; however, there is limited information with regard to the key strength and power variables that influence start performance during sprint swimming. In light of the above, this study aimed to examine the key strength and power predicators of start performance in 50-m freestyle swimming. Eleven male British international sprint swimmers (age 21.3 ± 1.7 years; mass 78.1 ± 11.2 kg; and height 1.8 ± 0.1 m) participated in this study. Within 1 week, swimmers performed the following tests: 3 repetition maximum (3RM) squat strength, countermovement jump (CMJ) on a portable force platform, and a measure of start time performance (time to 15 m under 50-m freestyle conditions). The start time was measured using a standard racing platform to which a portable force platform was mounted, and all starts were recorded using 2 cameras. This setup allowed for the quantification of time to 15 m, peak vertical force (PVF), and peak horizontal force (PHF). Data were analyzed using Pearson's product moment correlation with significance set at p < 0.05. Start time was significantly related to 1RM strength (r = -0.74), jump height (r = -0.69), peak (r = -0.85), and relative power (r = -0.66) (p < 0.05) but not rate of force development (r = -0.56, p > 0.05). Furthermore, lower body strength was a key determinant of jump height (r = 0.69), power (r = 0.78), PVF (r = 0.62), and PHF (r = 0.71) (p < 0.05). This study provides evidence of the importance of lower body strength and power to start time in international 50-m sprint swimmers.

Influence of postactivation potentiation on sprinting performance in professional rugby players.

After a bout of high-intensity exercise of short duration (preload stimulus), the muscle is in both a fatigued and potentiated (referred to as postactivation potentiation [PAP]) state. Consequently, subsequent muscle performance depends on the balance of these 2 factors. Although research has shown PAP to be an effective method of increasing power during both the squat jumps, little data exist on its effect on more functional activities such as sprinting. The present study aimed to determine the effect of PAP on sprint performance in professional rugby players. Sixteen professional male rugby players performed 5 10-m sprints (with a 5-m split): baseline, 4, 8, 12, and 16 minutes after the preload stimulus (1 set of 3 repetitions of the back squat at 91% 1 Repetition Maximum [RM]). There was no significant time effect over the duration of the study with regard to 5-m (p = 0.175) and 10-m sprint times (p = 0.401). However, when individual responses to PAP were taken into account, a significant improvement in sprint performance was observed over both 5 (Baseline: 1.09 +/- 0.06s vs. Best time: 1.05 +/- 0.05s, p = 0.002) and 10 m (Baseline: 1.83 +/- 0.08s vs. Best time: 1.79 +/- 0.08s, p = 0.003) compared with the baseline sprint. We conclude that sprinting performance is enhanced after a preload stimulus providing adequate and individualized recovery is given between the 2 activities, and this may have important implications for training speed.

Optimal loading for the development of peak power output in professional rugby players.

The ability to develop high levels of muscular power is considered an essential component of success in many sporting activities; however, the optimal load for the development of peak power during training remains controversial. Our aim in the present study was to determine the optimal load required to observe peak power output during the ballistic bench throw (BBT) and squat jump (SJ) in professional rugby players. Forty-seven, professional, male, rugby players of (mean +/- SD) mass 101.3 +/- 12.8 kg and height 1.82 +/- 0.08 m volunteered and gave informed consent for this study, which was approved by a university ethics committee. Players performed BBT at loads of 20, 30, 40, 50, and 60% of their predetermined 1 repetition maximum (1RM) and SJ at loads of 0, (body mass only), 20, 30, 40, 50, and 60% of their predetermined 1RM in a randomized and balanced order. Power output (PO) was determined by measurement of barbell displacement with subsequent calculation of velocity, force, and power. Relative load had a significant effect on PO for both the BBT (effect size eta(2): 0.297, p < 0.001) and SJ (Effect Size eta(2): 0.709, p < 0.001). Peak power output was produced when the athletes worked against an external load equal to 30% 1RM for the upper body and 0% 1RM for the lower body.

Complex training in professional rugby players: influence of recovery time on upper-body power output.

After a bout of heavy resistance training (HRT), skeletal muscle is in both a fatigued and potentiated state. Subsequent muscle performance depends on the balance between these 2 factors. To date, there is no uniform agreement about the recovery time required between the HRT and subsequent muscle performance to gain performance benefits in the upper body. The aim of the present study was to determine the recovery time required to observe enhanced upper-body muscle performance after HRT (i.e., complex training). Twenty-six professional rugby players performed a ballistic bench press (BBP) at baseline and at approximately 15 seconds and 4, 8, 12, 16, 20, and 24 minutes after HRT (3 sets of 3 repetitions at 87% 1 repetition maximum). Peak power output (PPO) and throw height were determined for all BBPs. A significant time effect with regard to PPO (F = 29.145, partial Eta2 = 0.538, p < 0.01) and throw height (F = 17.362, partial Eta2 = 0.410, p < 0.01) was observed. Paired comparisons indicated a significant decrease in PPO and throw height in the BBP performed approximately 15 seconds after the HRT compared with the baseline BBP. After 8 minutes of recovery from the HRT, both PPO and throw height were significantly higher than the PPO and throw height recorded at baseline (e.g., PPO: 879 +/- 100 vs. 916 +/- 116 W, p < 0.01). It was concluded that muscle performance can be significantly enhanced after bouts of HRT during a BBP providing that adequate recovery (8 min) is given between the HRT and the explosive activity.

Postactivation potentiation in professional rugby players: optimal recovery.

Following a bout of high-intensity exercise of short duration (preload stimulus), the muscle is in both a fatigued and a potentiated (referred to as postactivation potentiation) state. Consequently, subsequent muscle performance depends on the balance between these 2 factors. To date, there is no uniform agreement about the optimal recovery required between the preload stimulus and subsequent muscle performance to gain optimal performance benefits. The aim of the present study was to determine the optimal recovery time required to observe enhanced muscle performance following the preload stimulus. Twenty-three professional rugby players (13 senior international players) performed 7 countermovement jumps (CMJs) and 7 ballistic bench throws at the following time points after a preload stimulus (3 repetition maximum [3RM]): baseline, approximately 15 seconds, and 4, 8, 12, 16, and 20 minutes. Their peak power output (PPO) was determined at each time point. Statistical analyses revealed a significant decrease in PPO for both the upper (856 +/- 121 W vs. 816 +/- 121 W, p < 0.001) and the lower (4,568 +/- 509 W vs. 4,430 +/- 495 W, p = 0.005) body when the explosive activity was performed approximately 15 seconds after the preload stimulus. However, when 12 minutes was allowed between the preload stimulus and the CMJ and ballistic bench throws, PPO was increased by 8.0 +/- 8.0% and 5.3 +/- 4.5%, respectively. Based on the above results, we conclude that muscle performance (e.g., power) can be significantly enhanced following a bout of heavy exercise (preload stimulus) in both the upper and the lower body, provided that adequate recovery (8-12 minutes) is given between the preload stimulus and the explosive activity.

Reliability and detecting change following short-term creatine supplementation: comparison of two-component body composition methods.

The purpose of the present study was twofold: firstly, to assess the reliability of various body composition methods, and secondly, to determine the ability of the methods to estimate changes in fat-free mass (FFM) following creatine (Cr) supplementation. Fifty-five healthy male athletes (weight 78.3 +/- 10.3 kg, age 21 +/- 1 years) gave informed consent to participate in this study. Subjects' FFM was estimated by hydrostatic weighing (HW), air-displacement plethysmography (ADP), bioelectrical impedance analysis (BIA), near-infrared spectroscopy (NIR), and anthropometric measurements (ANTHRO). Measurements were taken on 2 occasions separated by 7 days to assess the reliability of the methods. Following this, 30 subjects returned to the laboratory for an additional test day following 7 days of Cr supplementation (20 g.d(-1) Cr + 140 g.d(-1) dextrose) to assess each method's ability to detect acute changes in FFM. In terms of reliability, we found excellent test-retest correlations for all 5 methods, ranging from 0.983 to 0.998 (p < 0.001). The mean biases for the 5 methods were close to 0 (range -0.1 to 0.3 kg) and their 95% limits of agreement (LOAs) were within acceptable limits (HW = -1.1 to 1.7 kg; ADP = -1.1 to 1.2 kg; BIA = -1.0 to 1.0 kg; NIR = -1.4 to 1.4 kg); however, the 95% LOAs were slightly wider for ANTHRO (-2.4 to 2.6 kg). Following Cr supplementation there was a significant increase in body mass (from 77.9 +/- 10.1 kg to 78.9 +/- 10.3 kg, p = 0.000). In addition, all 5 body composition techniques detected the change in FFM to a similar degree (mean change: HW = 0.9 +/- 0.6 kg; ADP = 0.9 +/- 0.6 kg; BIA = 0.9 +/- 0.6 kg; NIR = 0.8 +/- 0.5 kg; ANTHRO = 1.0 +/- 0.7 kg; intraclass correlation coefficient = 0.962). We conclude that between-day differences in FFM estimation were within acceptable limits, with the possible exception of ANTHRO. In addition, all 5 methods provided similar measures of FFM change during acute Cr supplementation.